In the manufacture of semiconductor devices, plasma etching may be performed using a processing gas for microfabrication of a thin film formed on a workpiece. The thin film may be, for example, a silicon compound film such as a silicon nitride film or a silicon oxide film, an organic film which is mainly composed of carbon and may be formed of amorphous carbon or a photoresist composition, or an inorganic film containing which is mainly composed of an inorganic material and may be formed of a polycrystalline silicon film or amorphous silicon. When one of the thin films of different types is determined as an etching target film and another thin film as a non-target film, it is necessary to selectively etch the etching target film avoiding the non-target film. That is, etching needs to be performed highly selectively. Also, it is recently demanded to further reduce an impact on the environment in the manufacture of the semiconductor devices.
As such, a plasma etching method for selectively etching a silicon oxide film on a substrate serving as a workpiece is suggested (e.g., see PTL 1 set forth below). PTL 1 discloses a plasma etching method that uses a plasma etching gas containing fluorocarbon with 3 or 4 carbon atoms having at least one unsaturated bond and/or ether bond and also having a bromine atom. This plasma etching method may selectively etch a silicon oxide film in an excellent manner by using the plasma etching gas having short atmospheric lifetime and relatively small impact on the environment.